Apparatus for making cores of magnetic material for electromagnetic coils



GAUTHIER APPARATUS FOR MAKING CORES OF MAGNETIC Jan. 20, 1948. M. C.

MATERIAL FOR ELECTROMAGNETIC COILS Filed Nov. 6, 1945 lNVENTOr? M.G.GAUTH/Ex? Patented Jan. 20, 1948 APPARATUS FOR MAKING CORES OF MAG-NETIC MATERIAL FOR ELECTROMAG- NETIC COILS Marcel C. Gauthier,Montclair, N. 1., assignor to Western Electric Company, Incorporated,New York, N. Y., a corporation of New York Application November 6, 1943,Serial No. 509,334

1 Claim. 1

This invention relates to an apparatus for making cores of magneticmaterial for electromagnetic coils and more particularly to an apparatusfor making laminated coils of magnetic alloys whose high magneticcharacteristics produced by heat treatment and annealing are damaged byeven a slight measure of cold working after annealing.

A very useful type of magnetic core for electromagnetic coils is made bywinding a flat strip or ribbon of suitable magnetic alloy flatwise onitself in successive coils about a suitably shaped arbor until thedesired cross-sectional area is attained. Such a core then is anunbroken annulus or ring, which will be circular, square, oblong or havesome other polygonal form according to the shape of the arbor used. Themagnetic path of such a core is continuous around the core and islaminated transversely, both desirable characteristics. If the core isto be circular, elliptical, or otherwise without flattened straightportions. there may be but little diniculty in making it generally asdescribed. However, if, as may frequently be the case, the core is tohave the form of a square or oblong with rounded corners and straightsides it may be dinicult to achieve satisfactorily straight sides andstill retain or develop the magnetic characteristics of the materialsatisfactorily. This is particularly so when the ribbon from which thecore is wound is made of one of the various high nickel alloys of irongenerally called Permalloy. When such a ribbon is wound on a rectangularmandrel or former the successive turns will lie snugly on each otheraround the corners of the mandrel, but will tend. because of theelasticity of the material of the ribbon. to arch away from the mandrelalong its straight faces.

An object of the present invention is to provide an apparatus for makingwound ribbon cores of magnetic material in annular shape with straightportions in which the straight portions will consist of closely opposedindividually straight portions of the ribbon having no inherent tendencyto curve.

With the above and other objects in view the invention may be embodiedin a device for use in making magnetic cores which comprises a framehaving two parallel, spaced, rigid bars, one of the bars being formedwith a pair of parallel spaced bores therethrough directed axiallytoward the other bar, in combination with a separate and removablyapplicable pressure tool having driving pins thereon to slide freely 2through the said bores of the one bar to squeeze a core positionedagainst the other bar.

The particular method of making magnetic cores hereinafter disclosed anddescribed forms no part of thepresent invention being disclosed andclaimed incopending application Serial No. 551,240, filed August 25,1944, (Patent No. 2,416,989, granted March 4, 1947), by the sameinventor as a division of the present application.

Other obiects and features of the invention will appear from thefollowing detailed description of one embodiment thereqgaken inconnection with the accompanying d1 wings in which the same referencenumerals are applied to identical parts in the several figures and inwhich Fig. l is a view in front elevation with parts broken away of adevice constructed in accordance with the invention;

Fig. 2 is a section on the line 2-2 of Fig. 1;

and

o lain or Lavite.

this.

Fig. 3 is a detached view of a mandrel and magnetic ribbon wound thereonbefore being compressed in the device of Fig. 1.

In making one form of laminar magnetic core in accordance with theinvention, a ll) of suitable magnetic material, e. g. Permalloy, iswound, as shown in Fig. 3, flatwise in successive turns on a mandrel Hof suitable heat resisting material, e. g. a ceramic such as porce- Inthis instance the mandrel is a rectangular oblong with rounded cornersand with straight sides between the rounded corners. A turn or two ofpaper tape l2 are wound on the mandrel and the metal ribbon I0 is woundover When the ribbon is wound on the mandrel, since the alloy of theribbon has more or less elastic stiffness, the turns will spring in somesuch fashion as is indicated in Fig. 3. departing more and more as thewinding continues from,

4 the desired fiatsided form.

The core as wound and shown in Fig. 3 is then laid, in the positionshown in Fig. 1, on the lower crossbar M of a rectangular, rigid, metalframe,

generally indicated at 18, standing on the bed IQ of a press whose ram20'is shown at the top of Fig. 1, but is not shown in Fig. 2. A pillowblock 2| is inserted between one end of the coil (the right end inFig. 1) and the adjacent upright member of the frame (upright H in Fig.A pillow block 22 is laid on the upper side of the wound core. Thepressure tool generally indicated at 24 is placed in position. This toolhas two vertical parallel driving pins 25 and 26 which pass throughcorresponding bores 21 and at ribbon 28 in the upper crossbar ii of theframe l8, the

bores being materially larger than the pins. The pin 25 is held in alower crosshead member 29 in a closefitting bore 30 counterbored at 31to receive and retain the head of the pin. The pin 26 is looselysupported and retained in an oversized bore 32 having an oversizedcounterbore 33 for the head of the pin. An upper crosshead member 34 issecured on the lower crosshead member 29 by screws 35, 35. The flatheads of the pins 25 and 26 bear flatly against the member 34 and areheld in place thereby, the pin 25 rigidly and the pin 26 with somefreedom to shift laterally if the spacing of the bores 21 and 28 variesslightly from frame to frame. The ram 20 of the press is then broughtdown on the tool 24 and acts through the pillow block 22 to squeeze theupper and lower sides of the wound core flat as shown in Fig. 1. One ormore suitable spacing blocks 36 and shims 31 are then inserted betweenthe pillow block 22 and the crossbar I5. The ram 20 is raised and thetool 24 removed, the block 22 being retained in position to hold thesides of the core fiat by the block or blocks 36 and shim or shims 31.

The frame 18 is then turned 90 clockwise to stand on the upright 11, nowresting horizontally on the press bed IS. The tool 24 is replaced underthe ram with its pins 25 and 26 passing respectively throughcorresponding bores I21 and I28 in the bar 16 of the frame and pressingagainst a pillow block 23 placed against what was the left end and isnow the top end of the core. fore and the ends of the core squeezed flatbetween the block 23 and the block 2 1. One or more spacing blocks I36and shims I31, I31 are inserted between the block 23 and the frame bar16. The ram is retired, and the tool 24 removed. The core is then heldlocked in the frame with its sides and ends flat as shown in Fig. 1.

The frame with the core thus locked in place and in proper shape withinit is then heat treated as necessary to develop the desired magneticcharacteristics of the metal of the core. For example, in the case ofone kind of Permalloy ribbon, the treatment consists in heating to about1975 F. for about an hour and then cooled slowly. One result of this isto develop The ram 20 is then brought down as bein the metal a very highmagnetic permeability, another is to burn out and wholly remove thepaper coils 12 between the mandrel II and the ribbon Ill thus making themandrel easily removable from the finished core; and a third is toanneal all internal stresses in the ribbon so that the turns will remainflat and snug along the straight portions of the core. The burning awayof the paper also releases the pressures on the spacing blocks andshims, so that ordinarily, when the assembly has cooled enough tohandle, the finished core and the spacer blocks and shims can be takenout of the frame with the fingers.

What is claimed is:

A device for use in making magnetic cores which comprises a frame havingtwo parallel, spaced, rigid bars, one of the bars being formed with apair of parallel spaced bores therethrough directed axially toward theother bar, in combination with a separate and removably applicablepressure tool having driving pins thereon to slide freely through thesaid bores of the one bar to squeeze a core positioned against the otherbar and a block to be placed between the said members and the core totransmit pressure therebetween, together with removable means to beplaced between the block and the said bar having the holes therein tomaintain pressure on the core when the tool is removed.

MARCEL C. GAUTHIER.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Date

